Method and device for producing feedstuff or organic fertilizer from edible waste material through low temperature, natural fermentation and drying process

ABSTRACT

A method and device for producing feed stuff or organic fertilizer from edible waste material, such as domestic and commercial food waste products in addition to marine, livestock and agriculture by-products resulting from the commercial production of food items, through a low temperature, natural fermentation and drying process is disclosed. In an embodiment, two mixing/crushing screw feeder units are inclinedly arranged within a chamber with the inclining directions of the two units being opposite to each other. Two mixing screw feeder units individually and downwardly extend from the overlapping inclined end of one of the two mixing/crushing units to the underlapping declined end of the other mixing/crushing unit. In another embodiment, two oppositely rotatable screw feeders, individually consisting of a drive shaft with two helical screws rotating upon the shaft in opposite directions, are horizontally arranged in the chamber.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates, in general, to a disposal ofedible waste material consisting of domestic and commercial food wasteproducts in addition to marine, livestock and agriculture by-productsresulting from the commercial production of food items and, moreparticularly, to a method and device for producing feed stuff or organicfertilizer from such waste material by naturally fermenting and dryingthe material at low temperatures while uniformly mixing and crushingsuch material.

[0003] 2. Description of the Prior Art

[0004] In accordance with the elevation in the standard of living, theamount of edible waste material, such as domestic and commercial foodwaste products in addition to marine, livestock and agricultureby-products resulting from the commercial production of food items,rapidly increases, so that an issue arises concerning the disposal ofsuch waste material.

[0005] In an effort to effectively treat such waste material, severaltypes of devices, used for producing feed stuff or organic fertilizerfrom such waste material through a fermentation and drying process, areproposed as disclosed in Korean Patent Publication Nos. 93-1480, 94-9484and 96-4473.

[0006] In the above Korean devices, a fermenting/drying chamber isvertically, horizontally or inclinedly positioned with a drive shaftbeing axially and rotatably set in the chamber. An agitating blade orhelical screw is provided on the drive shaft, thus stirring, mixing andcrushing edible waste material while moving the material within thechamber, thus producing feed stuff or organic fertilizer from ediblewaste material.

[0007] However, such a typical device, with the agitating blade orhelical screw, is problematic in that the device only partially loadswaste material on a part in the chamber due to a structural limit of theagitating blade or the helical screw. Therefore, it is impossible forthe device to uniformly or effectively stir or mix the waste material.In order to overcome such a problem, the helical screw may be designedfor rotating upon the drive shaft in opposite directions and havingdifferent diameters. The helical screw, with opposite spiral directionsand different diameters, somewhat effectively mixes edible wastematerial while moving the material in opposite directions. However, sucha helical screw, with opposite spiral directions and differentdiameters, also fails to uniformly mix or crush waste material since thematerial is heavy and bulky, thus sinking under its own weight.

[0008] Due to such a nonuniformity in mixing and crushing the ediblewaste material in the chamber, the typical device fails to completelyferment or dry the waste material into feed stuff or organic fertilizerand reduces the quality of resulting feed stuff or organic fertilizer.It is extremely impractical to provide animals with such a low qualityfeed stuff or organic fertilizer.

[0009] Another problem experienced in the above devices resides in thatthe agitating blade or helical screw in the chamber is partiallyoverloaded with heavy and bulky material and this results in exceedingconsumption of electric power and shortens the expected life span ofthese devices.

SUMMARY OF THE INVENTION

[0010] Accordingly, the present invention has been made keeping in mindthe above problems occurring in the prior art, and an object of thepresent invention is to provide a method and device for producing feedstuff or organic fertilizer from edible waste material by naturallyfermenting, drying and sterilizing the material at low temperatureswhile uniformly and effectively mixing and crushing the material in achamber.

[0011] Another object of the present invention is to provide a methodand device for producing feed stuff or organic fertilizer from ediblewaste material through a low temperature, natural fermentation anddrying process suitable for almost completely fermenting and drying thematerial into high quality feed stuff or organic fertilizer.

[0012] A further object of the present invention is to provide a devicefor producing feed stuff or organic fertilizer from edible wastematerial through a low temperature, natural fermentation and dryingprocess, which effectively mixes and crushes the material whileuniformly loading the heavy and bulky material on a mixing/crushingmeans, thereby being effectively used for a lengthy period of time whilebeing economical in the consumption of electricity.

[0013] In order to accomplish the above object, the primary embodimentof the present invention provides a method of producing feed stuff ororganic fertilizer from edible waste material, consisting of domesticand commercial food waste products in addition to marine, livestock andagriculture by-products resulting from the commercial production of fooditems, through a low temperature, natural fermentation and dryingprocess in a fermenting/drying chamber, comprising the steps of: movingthe waste material upwardly along an inclinedly arranged first screwfeeder unit from a declined end to an inclined end of the unit whilemixing and crushing the material by helical screws of the unit prior topassing the material to an inclined end of an inclinedly arranged secondscrew feeder unit; moving the waste material downwardly along the secondunit from the inclined end to a declined end of the second unit whilemixing the material by helical screws of the second unit prior topassing the material to a declined end of an inclinedly arranged thirdscrew feeder unit; moving the waste material upwardly along the thirdunit from the declined end to an inclined end of the third unit whilemixing and crushing the waste material by helical screws of the thirdunit prior to passing the material to an inclined end of an inclinedlyarranged fourth screw feeder unit; moving the waste material downwardlyalong the fourth unit from the inclined end to a declined end of thefourth unit while mixing the material by helical screws of the fourthunit prior to passing the material to the declined end of the firstunit, thus allowing the waste material to be repeatedly processed by thefirst to fourth units until the material is appropriately fermented anddried into feed stuff or organic fertilizer.

[0014] In the above method, the first and third screw feeder unitsindividually consist of alternately and parallely arranged first andsecond screw feeders rotatable in opposite directions, thus moving thewaste material upwardly while mixing and crushing the material.

[0015] In accordance with another embodiment of this invention, themethod comprises the step of: repeatedly moving the waste material alongtwo horizontally and parallely arranged screw feeders outwardly andinwardly while mixing and crushing the material by helical screws of thetwo screw feeders rotated in opposite directions.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The above and other objects, features and other advantages of thepresent invention will be more clearly understood from the followingdetailed description taken in conjunction with the accompanyingdrawings, in which:

[0017]FIG. 1 is a longitudinal sectioned view of a device in accordancewith the primary embodiment of the present invention;

[0018]FIG. 2 is a cross sectioned view of the device of FIG. 1;

[0019]FIG. 3 is a plan view showing the operation of the device of FIG.1 when the device mixes and crushes waste material;

[0020]FIGS. 4a and 4 b are views showing the construction and operationof a power transmission unit for each mixing/crushing unit included inthe device of FIG. 1;

[0021]FIG. 5 is a longitudinal sectioned view of a device in accordancewith the second embodiment of the present invention;

[0022]FIGS. 6a and 6 b are views showing the construction and operationof a mixing/crushing unit installed in the device of FIG. 5, the unitconsisting of two mixing/crushing screw feeders in accordance with anembodiment of this invention; and

[0023]FIGS. 7a and 7 b are views showing the construction and operationof a mixing/crushing unit installed in the device of FIG. 5, the unitconsisting of three mixing/crushing screw feeders in accordance withanother embodiment of this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024]FIGS. 1 and 2 are sectional views of a device, which produces highquality feed stuff or organic fertilizer from edible waste material bynaturally fermenting and drying the material at low temperatures, inaccordance with the primary embodiment of the present invention.

[0025] The device of FIGS. 1 and 2 ferments and dries waste material,consisting of domestic and commercial food waste products in addition tomarine, livestock and agriculture by-products resulting from thecommercial production of food items, into feed stuff or organicfertilizer as follows.

[0026] Prior to starting the device, waste material is introduced into afermenting/drying chamber 5 through a waste material entrance 4.

[0027] When assuming that the waste material is primarily mixed andcrushed at the underlapping declined end of a first screw feeder unit 10inside the chamber 5, the material moves upwardly along the first unit10 to the overlapping inclined end of that unit 10 while being mixed andcrushed by the unit 10. At the overlapping inclined end of the firstunit 10, the material is dropped onto the underlapping inclined end of asecond screw feeder unit 20.

[0028] In the first unit 10, a plurality of, for example, a pair offirst and a pair of second screw feeders 12 and 14 are arranged inparallel to each other. The above screw feeders 12 and 14 are rotatablein opposite directions, thus effectively mixing and crushing thematerial while moving it.

[0029] The waste material, thereafter, moves downwardly along the secondunit 20 to the overlapping declined end of the unit 20 while beingmixed. At the declined end of the unit 20, the material is dropped ontothe underlapping declined end of a third screw feeder unit 10′.

[0030] Thereafter, the material moves upwardly along the third unit 10′to the overlapping inclined end of that unit 10′ while being mixed andcrushed. At the inclined end of the unit 10′, the material is droppedonto the underlapping inclined end of a fourth screw feeder unit 20′.

[0031] In the same manner as that described for the first unit 10, aplurality of, for example, a pair of first and a pair of second screwfeeders 12 and 14 are arranged in the third unit 10′ and are rotatablein opposite directions, so that the third unit 10′ effectively mixes andcrushes the waste material while moving it.

[0032] The waste material, thereafter, moves downwardly along the fourthunit 20′ to the overlapping declined end of that unit 20′ while beingmixed prior to being dropped onto the underlapping declined end of thefirst unit 10. Upon receiving the waste material, the first unit 10moves the material upwardly while mixing and crushing it, thus startinganother cycle of mixing and crushing the waste material. Such a cycle isrepeated until the material is appropriately and almost completelyfermented and dried into feed stuff or organic fertilizer.

[0033] In the device, the first and third units 10 and 10′ are for bothmixing and crushing the waste material, while the second and fourthunits 20 and 20′ are for only mixing the waste material.

[0034] The construction of the above device will be described in detailwith reference to the accompanying drawings.

[0035] As shown in FIGS. 1 to 4 b showing the device according to theprimary embodiment of this invention, the device has a fermenting/dryingchamber 5 where waste material is repeatedly fermented and dried intofeed stuff or organic fertilizer.

[0036] In the chamber 5, two mixing/crushing units: first and thirdscrew feeder units 10 and 10′ individually consisting of four screwfeeders, are oppositely and inclinedly arranged with the incliningdirections of the two units 10 and 10′ being diametrically opposite toeach other, thus forming an X-shaped profile viewed from the front asshown in FIG. 1. Of the four screw feeders of each unit 10 or 10′, twoare called first screw feeders 12, while the other two are called secondscrew feeders 14. The first and second screw feeders 12 and 14 arealternately and parallely arranged and are designed for being rotatablein opposite directions. For ease of description, of the two first screwfeeders 12, one positioned at the outside is called an outside firstscrew feeder, while the other positioned at the inside is called aninside first screw feeder. The two second screw feeders 14 arerespectively called inside and outside screw feeders in the same manneras that described for the first screw feeders 12. Each of the two units10 and 10′ moves waste material upwardly from the underlapping declinedend to the overlapping inclined end while mixing and crushing thematerial.

[0037] Two mixing units: second and fourth screw feeder units 20 and 20′individually consisting of two parallel screw feeders 22, are oppositelyand inclinedly arranged in the chamber 5. In such a case, the secondunit 20 extends downwardly from the overlapping inclined end of thefirst unit 10 to the underlapping declined end of the third unit 10′while the fourth unit 20′ extends downwardly from the overlappinginclined end of the third unit 10′ to the underlapping declined end ofthe first unit 10.

[0038] It should be noted that in the description of all overlapping andunderlapping ends, whether inclined or declined, the overlapping andunderlapping ends are spaced apart by a certain distance. That is, theydo not come into contact with each other.

[0039] In the above device, the four screw feeders 12 and 14 of eachmixing/crushing unit 10, 10′ are commonly operated by the rotating forceof a first drive means (A), such as a motor. The rotating force of thefirst drive means (A) is transmitted to the four screw feeders 12 and 14through a first power transmission unit of FIGS. 4a and 4 b. As shown inFIGS. 4a and 4 b, the first power transmission unit for eachmixing/crushing unit 10, 10′ comprises one middle sprocket 15 a and aplurality of end sprockets 13 a and 15 b. That is, the end 13 of eachfirst screw feeder 12 has a first end sprocket 13 a, while the end 15 ofeach second screw feeder 14 has a second end sprocket 15 b. The middlesprocket 15 a is fixed to the inside second screw feeder 14 at aposition inside the second end sprocket 15 b of the screw feeder 14. Thetwo end sprockets 13 a of the first screw feeders 12 are commonlyconnected to a drive sprocket (A-a) of the first drive means (A) througha first chain C1 so as to rotate the first screw feeders 12 in the samedirection. In order to allow the inside second screw feeder 14 to berotatable in a direction reversed to that of the first screw feeders 12,the first chain C1 also engages with the middle sprocket 15 a of theinside second screw feeder 14 prior to being wrapped around the endsprocket 13 a of the inside first screw feeder 12. The two end sprockets15 b of the second screw feeders 14 are connected to each other througha second chain C2 so as to rotate the second screw feeders 14 in thesame direction.

[0040] On the other hand, the two screw feeders 22 of each mixing unit20, 20′ are operated by the rotating force of a second drive means (A′),such as a motor. The rotating force of the second drive means (A′) istransmitted to the screw feeders 22 through a second power transmissionunit. As shown in FIG. 3, the second power transmission unit for each ofthe mixing units 20 and 20′ comprises two end sprockets 23 a which arerespectively fixed to the ends 23 of the two screw feeders 22. The twoend sprockets 23 a of the screw feeders 22 are commonly connected to adrive sprocket (A′-a) of the second drive means (A′) through a thirdchain C3 so as to rotate the two screw feeders 22 in the same direction.

[0041] In the primary embodiment of this invention, each powertransmission unit, used for transmitting the rotating force of eachdrive means A or A′ to an associated screw feeder unit 10, 10′, 20 or20′, forms a chain transmission system. However, it should be understoodthat another type of conventional power transmission system, such as abelt or gear transmission system, may be used in place of the chaintransmission system without affecting the functioning of this invention.

[0042] Either of the two mixing units 20 and 20′ extends to an exit 25of the fermenting/drying chamber 5, thus selectively discharging thefeed stuff or organic fertilizer to the outside of the chamber 5 throughthe exit 25. In the primary embodiment of FIG. 3, the second unit 20extends to the exit 25, so that the unit 20 selectively discharges theprocessed material or the feed stuff or organic fertilizer from thechamber 5 through the exit 25. When it is necessary to discharge theprocessed material from the chamber 5, the drive means (A′) for thesecond unit 20 is rotated in a reversed direction, so that the two screwfeeders 22 of the unit 20 are rotated in a reversed direction, thusdischarging the processed material from the chamber 5.

[0043] An insulating material 6 covers both the bottom of the four units10, 10′, 20 and 20′ and the housing of the chamber 5 as shown in FIGS. 1and 2, thus thermally insulating the chamber 5 from the atmosphere. Aheating pipe 6 a is arrayed in the insulating material 6, thus allowinghot air from a hot air source (not shown) to circulate throughout theheating material 6.

[0044] In the drawings, the reference numerals 7 and 8 denote an airintake port and an air suction port for the chamber 5, respectively.

[0045] The operational effect of the above device will be describedhereinbelow.

[0046] In order to produce feed stuff or organic fertilizer from ediblewaste material using the device of this invention, an appropriate amountof edible waste material, consisting of domestic and commercial foodwaste products in addition to marine, livestock and agricultureby-products resulting from the commercial production of food items, isintroduced into the fermenting/drying chamber 5 through the entrance 4.

[0047] Thereafter, a blower fan 9 is activated, so that air forciblycirculates inside the chamber 5 in a direction from the air intake port7 to the air suction port 8.

[0048] In addition, the hot air source is activated in order to increasethe temperature of the chamber 5. That is, when the hot air source isactivated, hot air from the source circulates through the heating pipe 6a, thus increasing the temperature inside the chamber 5 to a levelsuitable for naturally fermenting and drying the waste material withinthe chamber 5.

[0049] Thereafter, the first and second drive means A and A′ for thefour units 10, 10′, 20 and 20′ are activated, so that the units 10, 10′,20 and 20′ is operated as will be described hereinbelow.

[0050] For ease of description, the operation of the screw feeder units10, 10′, 20 and 20′ is described with the waste material being primarilymixed and crushed at the underlapping declined end of the first unit 10.

[0051] The first and second screw feeders 12 and 14 of the first unit 10are rotated in opposite directions by the first drive means (A). Thatis, the screw feeders 12 and 14 are rotated clockwise andcounterclockwise respectively as shown in FIG. 2, so that the wastematerial moves upwardly along the first unit 10 from the declined end tothe inclined end of the unit 10 while being mixed and crushed by thehelical screws of that unit 10.

[0052] The waste material is, thereafter, dropped onto the underlappinginclined end of the second unit 20 and moves downwardly along the unit20 to the overlapping declined end of that unit 20 while being mixed bythe helical screws of that unit 20. In such a case, the two screwfeeders 22 of the unit 20 are rotated in a normal direction. The wastematerial is dropped from the second unit 20 onto the underlappingdeclined end of the third unit 10′.

[0053] The waste material moves upwardly along the third unit 10′ to theoverlapping inclined end of that unit 10′ while being mixed and crushedwith the first and second screw feeders 12 and 14 of that unit 10′ beingrotated in opposite directions. The waste material is, thereafter,dropped onto the underlapping declined end of the fourth unit 20′. Thewaste material moves downwardly along the fourth unit 20′ to theoverlapping declined end of that unit 20′ prior to being dropped ontothe declined end of the first unit 10.

[0054] During the operation of the device, the first and second screwfeeders 12 and 14 of the first unit 10 are rotated in oppositedirections as described above. Edible waste material thus comes intofrictional contact with the screw feeders 12 and 14, thereby generatinglow temperature heat. Such low temperature heat not only forms adesirable condition suitable for naturally fermenting and drying thewaste material, but also sterilizes the material.

[0055] In addition, the waste material is effectively and uniformlymixed and crushed by the first to fourth units 10, 10′, 20 and 20′, sothat the natural fermentation and drying effect of the device is notpartially affected on the waste material, but is uniformly affected onall the waste material.

[0056] When the waste material is completely processed into feed stuffor organic fertilizer by the device, the feed stuff or organicfertilizer is discharged to the outside of the chamber 5 through theexit 25. When it is necessary to discharge the feed stuff or organicfertilizer from the chamber 5, the exit 25 is opened prior to startingthe drive means (A′) for the second unit 20 in a reversed direction. Thetwo screw feeders 22 of the second unit 20 are thus rotated in thereversed direction and discharge the feed stuff or organic fertilizerfrom the chamber 5 into a feed stuff or organic fertilizer container(not shown) outside the chamber 5 through the exit 25.

[0057] FIGS. 5 to 6 b are views of a device for naturally fermenting anddrying edible waste material into feed stuff or organic fertilizer atlow temperatures in accordance with the second embodiment of the presentinvention.

[0058] The device according to the second embodiment ferments and driesedible waste material into feed stuff or organic fertilizer as follows.

[0059] Prior to starting the device, edible waste material, such asdomestic and commercial food waste products in addition to marine,livestock and agriculture by-products resulting from the commercialproduction of food items, is introduced into a fermenting/drying chamber35 of the device through an entrance 34.

[0060] When assuming that the waste material is primarily mixed andcrushed at both ends of first and second screw feeders 40 and 40′ insidethe chamber 35, the waste material moves along the two screw feeders 40and 40′ from the outside to the center while being mixed and crushed bythe helical screws of the two feeders 40 and 40′.

[0061] Thereafter, the waste material moves along the two screw feeders40 and 40′ from the center to the outside while being mixed and crushedby the helical screws of the feeders 40 and 40′. Such an oppositedirectional movement of the waste material along the screw feeders 40and 40′ is repeated until the waste material is appropriately fermentedand dried into feed stuff or organic fertilizer.

[0062] In such a case, the two screw feeders 40 and 40′ are rotated inopposite directions, thus effectively mixing and crushing the wastematerial while moving it. Therefore, the above device naturally fermentsand dries the waste material at low temperatures, thus producing highquality feed stuff or organic fertilizer.

[0063] The construction of the above device will be described in detailwith reference to FIGS. 5 to 6 b.

[0064] As shown in the drawings, the device has a fermenting/dryingchamber 35 where edible waste material is fermented and dried into feedstuff or organic fertilizer.

[0065] First and second screw feeders 40 and 40′ are horizontally andparallely arranged inside the chamber 35. The two screw feeders 40 and40′ individually comprise a drive shaft 43 with two helical screws 42and 44 rotating upon the drive shaft 43 in opposite directions at bothsides of the shaft 43. In addition, the rotating direction of thehelical screws 42 and 44 upon the drive shaft of the first screw feeder40 is opposite to that of the second screw feeder 40′. The above screwfeeders 40 and 40′ are also designed for being rotated in oppositedirections.

[0066] The two screw feeders 40 and 40′ are operated by the rotatingforce of a drive means (A″), such as a motor. The rotating force of thedrive means (A″) is transmitted to the two screw feeders 40 and 40′through a third power transmission unit of FIG. 6a. As shown in FIG. 6a,the third power transmission unit for the two screw feeders 40 and 40′comprises two gears 43 a each of which is fixed to the end 43 of eachscrew feeder 40 or 40′. The two gears 43 a commonly engage with a drivegear (A″-a) of the drive means (A″) at both sides of the gear (A″-a),thus being rotatable in opposite directions.

[0067] In the second embodiment, the power transmission unit, used fortransmitting the rotating force of the drive means (A″) to the screwfeeders 40 and 40′, forms a gear transmission system. However, it shouldbe understood that another type of conventional power transmissionsystem, such as a belt or chain transmission system, may be used inplace of the gear transmission system without affecting the functioningof this invention.

[0068] In the above device, the number of screw feeders may be changedin order to meet the amount of edible waste material to be processed bythe device. That is, three screw feeders 40, 40′ and 40″ may behorizontally and parallely arranged inside the chamber 35 as shown inFIGS. 7a and 7 b. As shown in the drawings, the additional screw feederor the third screw feeder 40″ is arranged aside by the second screwfeeder 40′ at a position opposite to the first screw feeder 40. That is,the first and third screw feeders 40 and 40″ are parallely positioned atboth sides of the second screw feeder 40′. The rotational direction ofthe helical screws upon the drive shaft of the third screw feeder 40″remains the same as that of the second screw feeder 40′. In theembodiment of FIGS. 7a and 7 b, the power transmission unit for thethree screw feeders 40, 40′ and 40″ has two end sprockets 43 b inaddition to the construction described for the embodiment of FIGS. 6aand 6 b. The two end sprockets 43 b are individually mounted to the endof the rotating shaft 43 of each of the second and third screw feeders40′ and 40″. The two sprockets 43 b are also connected to each otherthrough a fourth chain C4 so as to rotate the two screw feeders 40′ and40″ in the same direction.

[0069] In the drawings, the reference numeral 6 a denotes a heatingpipe, which is arrayed in the insulating material 6, thus allowing hotair from a hot air source (not shown) to circulate throughout theheating material 6. The numerals 34 and 32 denote an entrance and anexit, both being provided at the chamber 35 so as to inlet and dischargewaste material into and from the chamber 35, respectively. The numerals37 and 38 denote an air intake port and an air suction port for thechamber 35, respectively. The numeral 9 denotes a blower fan whichforcibly circulates air inside the chamber 5 in a direction from the airintake port 7 to the air suction port 8.

[0070] The operational effect of the above device of FIGS. 5 to 6 b willbe described hereinbelow.

[0071] In order to produce feed stuff or organic fertilizer from ediblewaste material by fermenting and drying the material using the abovedevice, an appropriate amount of waste material, such as domestic andcommercial food waste products in addition to marine, livestock andagriculture by-products resulting from the commercial production of fooditems, is introduced into the fermenting/drying chamber 35 through theentrance 34.

[0072] Thereafter, the blower fan 39 is activated, thereby forciblycirculating air within the chamber 35 in a direction from the air intakeport 37 to the air suction port 38.

[0073] In addition, the hot air source is activated in order to increasethe temperature of the chamber 35. That is, when the hot air source isactivated, hot air from the source circulates through the heating pipe 6a, thus increasing the temperature of the chamber 35 to a level suitablefor naturally fermenting and drying the waste material in the chamber35.

[0074] Thereafter, the drive means A″ for the screw feeders 40 and 40′are activated, thus starting the two screw feeders 40 and 40′. In such acase, the two screw feeders 40 and 40′ are rotated in oppositedirections.

[0075] As described above, the two screw feeders 40 and 40′, used formixing and crushing edible waste material, individually comprise a driveshaft 43 with two helical screws 42 and 44 rotating upon the drive shaft43 in opposite directions at both sides of the shaft 43. Therefore, thewaste material in the chamber 35 moves along the two screw feeders 40and 40′ from the outside to the center while being mixed and crushed bythe helical screws of the screw feeders 40 and 40′. Thereafter, thewaste material moves along the two screw feeders 40 and 40′ from thecenter to the outside while being mixed and crushed. Such an oppositedirectional movement of the waste material along the screw feeders 40and 40′ is repeated until the waste material is completely fermented anddried into feed stuff or organic fertilizer.

[0076] In such a case, the two screw feeders 40 and 40′ are rotated inopposite directions, thus effectively mixing and crushing the wastematerial while moving it. Therefore, the above device naturally fermentsand dries the waste material into feed stuff or organic fertilizer atlow temperatures.

[0077] During the operation of the device, the two screw feeders 40 and40′ are rotated in opposite directions by the drive means A″, so thatthe waste material comes into frictional contact with the screw feeders40 and 40′, thus generating low temperature heat. Such low temperatureheat not only forms a desirable condition suitable for naturallyfermenting and drying the waste material, but also sterilizes the wastematerial.

[0078] In addition, the waste material is effectively and uniformlymixed and crushed by the screw feeders 40 and 40′, so that the naturalfermentation and drying effect of the device is not partially affectedon the waste material, but is uniformly affected on all the wastematerial.

[0079] When the waste material in the chamber 35 is completely processedinto feed stuff or organic fertilizer by the device, the feed stuff ororganic fertilizer is discharged to the outside of the chamber 35through the exit 32.

[0080] On the other hand, the device of FIGS. 7a and 7 b is operated asfollows. That is, when the device is started, the first and second screwfeeders 40 and 40′ are rotated in opposite directions, while the thirdscrew feeder 40″ is rotated in the same direction as that of the secondscrew feeder 40′. During the operation of the above device, edible wastematerial in the chamber 35 moves along the first and second screwfeeders 40 and 40′ while being mixed and crushed by the helical screwsof the two feeders 40 and 40′ in the same manner as that described forthe embodiment of FIGS. 6a and 6 b. In the device of FIGS. 7a and 7 b,the waste material also moves along the third screw feeder 40″, so thatthe device more effectively and uniformly mixes and crushes the wastematerial in comparison with the device of FIGS. 6a and 6 b. Therefore,the device of FIGS. 7a and 7 b improves the natural fermentation anddrying effect for the waste material. Of course, both the number androtating direction of the screw feeders of the above device may bechanged without affecting the functioning of this invention.

[0081] As described above, the present invention provides a method anddevice for naturally fermenting, drying and sterilizing edible wastematerial, consisting of domestic and commercial food waste products inaddition to marine, livestock and agriculture by-products resulting fromthe commercial production of food items, at low temperatures whileuniformly and effectively mixing and crushing the waste material, thusproducing high quality feed stuff or organic fertilizer from such wastematerial.

[0082] The device of this invention uniformly distributes edible wastematerial in a fermenting/drying chamber without allowing the heavy andbulky waste material to be partially overloaded on a mixing/crushingmeans inside the chamber. The device is thus effectively used for alengthy period of time while being economical in the consumption ofelectricity.

[0083] Although the preferred embodiments of the present invention havebeen disclosed for illustrative purposes, those skilled in the art willappreciate that various modifications, additions and substitutions arepossible, without departing from the scope and spirit of the inventionas disclosed in the accompanying claims.

What is claimed is:
 1. A method of producing feed stuff or organicfertilizer from edible waste material, consisting of domestic andcommercial food waste products in addition to marine, livestock andagriculture by-products resulting from the commercial production of fooditems, through a low temperature, natural fermentation and dryingprocess in a fermenting/drying chamber, comprising the steps of: movingthe waste material upwardly along an inclinedly arranged first screwfeeder unit from a declined end to an inclined end of said unit whilemixing and crushing the material by helical screws of the unit prior topassing the material to an inclined end of an inclinedly arranged secondscrew feeder unit; moving the waste material downwardly along saidsecond unit from the inclined end to a declined end of the second unitwhile mixing the material by helical screws of the second unit prior topassing the material to a declined end of an inclinedly arranged thirdscrew feeder unit; moving the waste material upwardly along the thirdunit from the declined end to an inclined end of said third unit whilemixing and crushing the waste material by helical screws of the thirdunit prior to passing the material to an inclined end of an inclinedlyarranged fourth screw feeder unit; moving the waste material downwardlyalong said fourth unit from the inclined end to a declined end of thefourth unit while mixing the material by helical screws of the fourthunit prior to passing the material to the declined end of said firstunit, thus allowing the waste material to be repeatedly processed by thefirst to fourth units until the material is appropriately fermented anddried into feed stuff or organic fertilizer.
 2. A method of producingfeed stuff or organic fertilizer from edible waste material, consistingof domestic and commercial food waste products in addition to marine,livestock and agriculture by-products resulting from the commercialproduction of food items, through a low temperature, naturalfermentation and drying process in a fermenting/drying chamber,comprising the steps of: repeatedly moving the waste material along twohorizontally and parallely arranged screw feeders outwardly and inwardlywhile mixing and crushing the material by helical screws of said twoscrew feeders rotated in opposite directions.
 3. A device for producingfeed stuff or organic fertilizer from edible waste material, consistingof domestic and commercial food waste products in addition to marine,livestock and agriculture by-products resulting from the commercialproduction of food items, through a low temperature, naturalfermentation and drying process in a fermenting/drying chamber,comprising: two mixing/crushing units oppositely and inclinedly arrangedin said chamber with inclining directions of said two units beingdiametrically opposite to each other, each of said two units consistingof alternately and parallely arranged first and second screw feedersrotatable in opposite directions, thus moving the waste materialupwardly while mixing and crushing the material; and two mixing unitsoppositely and inclinedly arranged in said chamber while respectivelyand downwardly extending from overlapping inclined ends to underlappingdeclined ends of the two mixing/crushing units, each of said mixingunits consisting of two screw feeders rotatable in the same direction,thus moving the waste material downwardly while mixing the materialprior to passing the material to the underlapping declined ends of themixing/crushing units.
 4. The device according to claim 3 , whereineither of the two mixing units extends to an exit of the chamber, thusselectively discharging processed waste material to the outside of saidchamber through the exit with the screw feeders of a selected mixingunit being rotated in a reversed direction.
 5. A device for producingfeed stuff or organic fertilizer from edible waste material, consistingof domestic and commercial food waste products in addition to marine,livestock and agriculture by-products resulting from the commercialproduction of food items, through a low temperature, naturalfermentation and drying process in a fermenting/drying chamber,comprising: two parallel screw feeders horizontally arranged in saidchamber, said two screw feeders being rotatable in opposite directionsand individually comprising a drive shaft, with two helical screwsrotating upon the drive shaft in opposite directions and the rotatingdirection of the helical screws of one of the two screw feeders beingopposite to that of the other screw feeder.